Can you please help with question 1 and 4

i) 24.305 u

iv) The number of protons determines an element's atomic number and is used to distinguish one element from another.

1) 24

2)protons

Explanation:

1) magnesium Ar

2) atomic number

8 carbon atoms forming single bonds with 18 hydrogen atoms; a triple bond exists between the third and fourth carbon atom from the right

explanation:

indium, and thallium have three electrons i think